AAV Ablates Neurogenesis in the Adult Murine Hippocampus

Abstract

Recombinant adeno-associated virus (rAAV) has been widely used as a viral vector across mammalian biology and has been shown to be safe and effective in human gene therapy. We demonstrate that neural progenitor cells (NPCs) and immature dentate granule cells (DGCs) within the adult murine hippocampus are particularly sensitive to rAAV-induced cell death. Cell loss is dose dependent and nearly complete at experimentally relevant viral titers. rAAV-induced cell death is rapid and persistent, with loss of BrdU-labeled cells within 18 hours post-injection and no evidence of recovery of adult neurogenesis at 3 months post-injection. The remaining mature DGCs appear hyperactive 4 weeks post-injection based on immediate early gene expression, consistent with previous studies investigating the effects of attenuating adult neurogenesis. In vitro application of AAV or electroporation of AAV2 inverted terminal repeats (ITRs) is sufficient to induce cell death. Efficient transduction of the dentate gyrus (DG)-without ablating adult neurogenesis-can be achieved by injection of rAAV2-retro serotyped virus into CA3. rAAV2-retro results in efficient retrograde labeling of mature DGCs and permits in vivo 2photon calcium imaging of dentate activity while leaving adult neurogenesis intact. These findings expand on recent reports implicating rAAV-linked toxicity in stem cells and other cell types and suggest that future work using rAAV as an experimental tool in the DG and as a gene therapy for diseases of the central nervous system (CNS) should be carefully evaluated. et al., 2015). These stem cells and their immature progeny are sensitive to environmental stimuli; their proliferation, development, and survival are regulated by multiple intrinsic and extrinsic factors, including experience, stress, and inflammation (Gonçalves et al., 2016a;Kempermann et al., 2015;Monje et al., 2003;Snyder et al., 2009;Vivar et al.). Numerous studies demonstrate that abDGCs are critical for maintaining the physiological activity of mature DGCs and contribute to hippocampus-dependent behaviors (Akers et al. 17

Ventro-dorsal Hippocampal Pathway Gates Novelty-Induced Contextual Memory Formation

“… 36 We found no cells in the GC layer three weeks after infection ( Figure 1 C), consistent with a recent report showing a high sensitivity to AAV-induced cell death specific for immature dentate GCs. 37 Only a small number of pyramidal cells in the CA3 area (7% of all labeled cells) expressed mCherry ( Figures S1 A and S1B). These results indicate that the vast majority of targeted cells in our approach are ventral MCs.…”

Hippocampal adult-born granule cells drive network activity in a mouse model of chronic temporal lobe epilepsy

“…Recent work 73 has reported that rAAVs impair neurogenesis in the adult mouse DG, with significant implications for functional recordings of GCs relying on rAAV for delivery of a genetically encode actuators or sensors. Given the design of our study, we believe these findings have limited relevance to the work presented here: principally, Johnston and colleagues 73 found that cells born two weeks or more prior to viral injection demonstrate no reduction, and in our study induction of Nestin expression by TMX occurred 2-3 weeks prior to injection with AAV1.Syn. GCaMP6f.…”

Sanfilippo Syndrome: Molecular Basis, Disease Models and Therapeutic Approaches

“…Among the qualities that make them good vectors, it is important to highlight that they are nonintegrative, nonpathogenic, and nonimmunogenic in humans, and have the capacity to infect nondividing cells providing long-term expression. However, a recent study shows that AAV can induce cell death in some neural cell types in the murine hippocampus, suggesting that these approaches should be carefully evaluated [ 110 ]. Nevertheless, in the last few years, several reports have been published concerning AAV-mediated therapy using different virus serotypes and delivery strategies.…”